1. Field of the Invention
This invention relates to an electro-acoustic transducer for sound reproduction and a sound reproducing system constructed with the use of the electro-acoustic transformer.
2. Description of the Related Art
Up to now, there is proposed an electro-acoustic transducer or a sound reproducing system supplied with acoustic signals in the form of electrical signals and adapted for converting the electrical signals into sound to realize sound reproduction, such as a headphone device or an earphone device.
The aforementioned electro-acoustic transducer comprises an electro-acoustic transducer unit for converting the acoustic signals into sound. The electro-acoustic transducer when constructed as the headphone device is adapted for supporting a pair of electro-acoustic transducer units in opposition to both auricles of the user.
The sound reproducing system also includes a pair of speaker units as the sound reproducing device arranged for converting the sound signals into sound. The speaker unit includes a speaker unit having a diaphragm and functioning as the sound reproducing unit. A speaker cabinet accommodates the speaker unit with the sound radiating side facing to outside. With the present sound reproducing system, the speaker device is arranged in front of and faces the listener to effect sound reproduction by the speaker device.
Meanwhile, with the above described electro-acoustic transducer, constructed as the headphone device, the electroacoustic transducer unit constituting the transducer faces the listener's tympanic membrane, so that standing waves are produced between the transducer unit and the tympanic membrane. The listener using such electro-acoustic transducer feels oppressed due to the standing waves or feels as if the sound source were within his head.
With the above described electro-acoustic transducer, the electro-acoustic transducer unit is supported for substantially closing the listener's external auditory meatus so that the listener using the electro-acoustic transducer feels unable to hear the external sound. Thus the use of the electro-acoustic transducer during walking on the road or driving a vehicle or car endangers safe walking or driving since the user can hardly recognize the outside situation.
With the above sound reproducing system, for optimum sound reproduction over a wide frequency range including the lower frequency range, it becomes necessary to increase the volume of the speaker cabinet constituting the speaker device or to increase the area of the diaphragm of the speaker unit. If the cabinet volume or diaphragm area is increased, the size of the apparatus increases.
On the other hand, with a sound reproducing system in which the size of the apparatus is increased to enable sound reproduction over a wide frequency range, it may be occasionally impossible to effect sound reproduction at a sufficient sound pressure in view of the inconveniences to the neighbors under the straitened or congested housing circumstances.